1. Field of the Invention
The technical scope of the invention is that of supports for gun sights for military vehicles.
2. Description of the Related Art
On a military vehicle equipped with a gun sight, firing accuracy is due in part to the capacity of the sight to have a known fixed position on the vehicle. This is particularly true for boresighting, for example.
The environment in which military vehicles equipped with a gun sight in a superstructure evolve often generates strong and intense vibrations due to travel and firing. The vertical vibratory stresses are the strongest and the most detrimental to the durability of the electronic equipment forming part of modern a gun sight.
Thus, a person skilled in the art wishing to integrate such a sight onto a military vehicle must fulfill contradictory requirements of assembly rigidity to ensure accuracy and stability of aim on the one hand, and requirements of flexibility and suspension to ensure the resistance and durability of the sight on the other.
A device to mount an inertial unit on an artillery system is known by patent EP2146176. In this device, a parallepipedic inertial unit is suspended by means of elastomer shock isolators placed on two of its parallel vertical faces. In this way, the unit damps the vertical stresses as well as the transversal stresses along an axis parallel to the faces on which the shock isolators are fixed.
This device suffers from drawbacks, however. The main drawback being that, in the case of a gun sight, the vibrations in the horizontal plane are such that a mounting that is not or is barely suspended is a requisite to contribute to firing accuracy. However, shock isolators such as those disclosed in EP2146176 leave a considerable degree of freedom in the horizontal plane which perturbs aiming. It must be noted that vibrations in a horizontal plane can generally be absorbed by gun sights.
A second drawback linked to the device proposed in EP2146176 comes from the fact that the elastomers generate hysteresis phenomena and are highly sensitive to climatic elements. Additionally, elastomers have a limited life and their properties evolve over time.
A damping device for a gun sight is known by patent EP0508684 that incorporates a single ring-shaped shock isolator made of a polymer material able to absorb shocks along a vertical axis. Travel in the plane perpendicular to the suspension axis is limited by the annular contact of a column supporting the sight with an insulating O-ring on a lower part of the sight.
The friction caused by the O-ring on the column generates hysteresis phenomena due to the adherence and friction of the O-ring. Additionally, the elastomer forming the O-ring has a limited life.